What do we know about plastic pollution in Brazilian aquatic ecosystems?

Due to the increasing use and inadequate disposal of plastic by humans, aquatic environments have become receptacles for pollutants such as plastic. This study aimed to perform an analysis of plastic particles pollution in Brazilian aquatic ecosystems with special attention to inland aquatic environments and fish in order to identify information gaps in this field. Manuscripts published in the last 21 years and indexed in the Web of Science database were consulted. A total of 185 met the proposed inclusion criteria, such as having empirical data, being conducted in Brazil, and dealing with plastic pollution. In general, the number of studies increases over the years, and this increasing number of publications is accompanied by declared financial support; the Southeast and Northeast regions are the regions that publish the most on the topic, with São Paulo, Rio de Janeiro, and Pernambuco being the main states; the main focus of the studies is the detection of plastic particles mainly in biota (51%) and sediment (34%), and the most frequent ecosystem is the marine (89%); regarding the taxa, the majority is about plastic detection in fish (75%). Only 18% of the papers studying fishes consider their bio-ecological data, and only 17% of the manuscripts carried out the chemical characterization of the particles. However, 99% of the papers considered the shape of the plastic particle. We emphasize the need for more research and grants for studies with Brazilian inland aquatic ecosystems on the effects of plastic particle pollution on freshwater fish. Regional and national research funding agencies are very important to encourage an increase in the number of grants and specific calls for studies on plastic pollution and its impact on freshwater biota, considering the different macro-regions in Brazil, especially in the northern region.

Organotropism of total mercury (THg) in Cichla pinima, ecological aspects and human consumption in fish from Amazon region, Brazil.

Specimens of the Cichla pinima are of ecological and economic importance in the Amazon region and are a good bioindicator species of Hg bioaccumulation. Adult specimens of Cichla pinima were obtained by fisheries in the Tapajós river region's impacted gold mining area. Tissues such as muscle, liver, skin, and gill were submitted for total mercury (THg) analysis. For hepatic bioavailability, assays were carried out in the whole liver and in the sub-cellular hepatic fraction. The weight-length relationship showed an equation of W = 2E - 06L3.3002 (R2 = 0.856) indicating an allometric growth. The mean THg values found in the muscle tissue of 676 ± 258 µg kg-1 were below the maximum limit established for human consumption, but were similar to Cichla fish from other areas impacted by Hg in the Amazon region. The trends of levels in the tissues were as follows: liver>muscle>gonads>skin>gill, with no significant differences between the gills and skin. A significant and positive correlation as rs = 0.65 was obtained between the THg contents in cytosolic fraction and the total hepatic THg (liver homogenate). However, only 7% of the THg were found and were available to the sub-cellular hepatic fraction. This profile can be an indicative of a hepatic cellular transference in fish exposed to high Hg levels in the Amazon region now that low concentrations of Hg have been found in the sub-cellular fraction. However, data of differential THg partition in the subcellular compartments should be considered, since others' hepatic fractions can act in the Hg linkage into the cell.